Today the hay that my camel was carrying had one straw too many - the camel's back broke, and so I had to muster up the gusto to automate.
For some time, I've been running a mail gateway and its worked out swimmingly for routing mail centrally with Postfix and Perdition. Incoming mail is relayed to different and separate back-end servers and mail-stores. It makes fighting spam and debugging problems SO much easier, not to mention that it reduces the amount of reverse DNS entries which need to be worried about.
HOWEVER, there is one serious problem: the relay_recipients_map table for Postfix to reduce backscatter spam. Since the recipients are defined in separate databases, I have been manually editing this table for awhile and half the time I forget to update it when I add a new address.
Now back to the poor camel - it had too much! There had to be an easier way and there is indeed. Thanks to the FEDERATED MySQL engine, I was able to aggregate the different backend datasources into several tables in a single database. From there I created a simple view, and voila, a single select query provides the complete and current dataset of all emails fit to receive. Now I just need to create a script to grab the result set and postmap it.